The PDA bible product I'm moving from provided the ability to highlight text in one of 5 colours and maintain that highlighting as part of my personal settings so that whenever the verse(s) are re-presented, the highlighting remains as I defined it.  This is a feature I used quite a bit.

This is coming in the next major release (2.0).  I think we're only supporting 4 colors, though.  Hope that's enough for you.